When snapshotting datadir, don't cross mounts

This should fix problems with snapshotting datadir when there is a
FUSE mount in there, for example.

1 files changed, 1 insertions, 1 deletions

diff --git a/yarn b/yarn
index af25d21..f2b48b5 100755
--- a/yarn
+++ b/yarn
@@ -454,7 +454,7 @@ class YarnRunner(cliapp.Application):
 
     def snapshot_datadir(self, tempdir, datadir, scenario, step_number, step):
         snapshot = self.snapshot_dir(tempdir, scenario, step, step_number)
-        cliapp.runcmd(['cp', '-a', datadir, snapshot])
+        cliapp.runcmd(['cp', '-ax', datadir, snapshot])
 
     def nice(self, name):
         # Quote a scenario or step name so it forms a nice filename.